“Plastics make ideal vessels for colonising microscopic organisms that could trigger disease if they come into contact with corals.

“Our work shows that plastic pollution is killing corals. Our goal is to focus less on measuring things dying and more on finding solutions”

“Plastic items – commonly made of polypropylene, such as bottle caps and toothbrushes – have been shown to become heavily inhabited by bacteria. This is associated with the globally devastating group of coral diseases known as white syndromes.”

She and colleagues from the US, Canada, Australia, Myanmar, Thailand and Indonesia report in the journal Science that between 2011 and 2014 they surveyed 124,000 reef-building corals from 159 reefs in the Asia-Pacific region.

One third of the reefs surveyed were polluted with plastic waste, the highest in Indonesian waters, the lowest off the Australian coast.

They calculate that, right now, the number of plastic bags, cups, bottles, toothbrushes and bits of packaging snagged on the reefs in the region could be 11.1 billion. By 2025, there could be 15.7 bn plastic objects stuck on the same reefs.

No return

And, they report, the presence of plastic was associated with a 20-fold increase in risk of disease, and in particular infections know to marine biologists as skeletal eroding band disease, white syndrome and black band disease.

The items snagged on the corals deprived them of sunlight and oxygen, and weakened the coral to the point at which invasive pathogens could gain a hold.

“What’s troubling about coral disease is that once the coral tissue loss occurs, it’s not coming back,” Dr Lamb said. “It’s like getting gangrene on your foot and there is nothing you can do to stop it from affecting your whole body.”

The Asia-Pacific region is home to more than 55% of the world’s coral reefs. Complex reef structures – reefs with branching corals, for instance – were eight times more likely to trap floating plastic waste.